diff --git a/lib/dns/geoip2.c b/lib/dns/geoip2.c
index 513e423fa5..c0ab66a241 100644
--- a/lib/dns/geoip2.c
+++ b/lib/dns/geoip2.c
@@ -326,7 +326,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 	geoip_state_t *state = NULL;
 	dns_geoip_subtype_t subtype;
 	const char *s = NULL;
-	int ret, i;
+	int ret;
 
 	REQUIRE(reqaddr != NULL);
 	REQUIRE(elt != NULL);
@@ -347,7 +347,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 	case dns_geoip_country_code:
 	case dns_geoip_city_countrycode:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "country", "iso_code", NULL);
+				     "country", "iso_code", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -356,7 +356,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 	case dns_geoip_country_name:
 	case dns_geoip_city_countryname:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "country", "names", "en", NULL);
+				     "country", "names", "en", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -365,7 +365,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 	case dns_geoip_country_continentcode:
 	case dns_geoip_city_continentcode:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "continent", "code", NULL);
+				     "continent", "code", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -374,7 +374,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 	case dns_geoip_country_continent:
 	case dns_geoip_city_continent:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "continent", "names", "en", NULL);
+				     "continent", "names", "en", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -383,7 +383,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 	case dns_geoip_region:
 	case dns_geoip_city_region:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "subdivisions", "0", "iso_code", NULL);
+				     "subdivisions", "0", "iso_code", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -392,7 +392,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 	case dns_geoip_regionname:
 	case dns_geoip_city_regionname:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "subdivisions", "0", "names", "en", NULL);
+				     "subdivisions", "0", "names", "en", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -400,7 +400,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 
 	case dns_geoip_city_name:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "city", "names", "en", NULL);
+				     "city", "names", "en", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -408,7 +408,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 
 	case dns_geoip_city_postalcode:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "postal", "code", NULL);
+				     "postal", "code", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -416,7 +416,7 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 
 	case dns_geoip_city_timezonecode:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "location", "time_zone", NULL);
+				     "location", "time_zone", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -425,14 +425,14 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 
 	case dns_geoip_city_metrocode:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "location", "metro_code", NULL);
+				     "location", "metro_code", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
 		break;
 
 	case dns_geoip_isp_name:
-		ret = MMDB_get_value(&state->entry, &value, "isp", NULL);
+		ret = MMDB_get_value(&state->entry, &value, "isp", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
@@ -442,8 +442,9 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 		INSIST(elt->as_string != NULL);
 
 		ret = MMDB_get_value(&state->entry, &value,
-				     "autonomous_system_number", NULL);
+				     "autonomous_system_number", (char *)0);
 		if (ret == MMDB_SUCCESS) {
+			int i;
 			s = elt->as_string;
 			if (strncasecmp(s, "AS", 2) == 0) {
 				s += 2;
@@ -455,14 +456,14 @@ dns_geoip_match(const isc_netaddr_t *reqaddr,
 
 	case dns_geoip_org_name:
 		ret = MMDB_get_value(&state->entry, &value,
-				     "autonomous_system_organization", NULL);
+				     "autonomous_system_organization", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}
 		break;
 
 	case dns_geoip_domain_name:
-		ret = MMDB_get_value(&state->entry, &value, "domain", NULL);
+		ret = MMDB_get_value(&state->entry, &value, "domain", (char *)0);
 		if (ret == MMDB_SUCCESS) {
 			return (match_string(&value, elt->as_string));
 		}